Orbicularis oculi
is a sphincter muscle around the eye and acts, in general, to narrow the eye opening and close the orbit of the eye. This muscle has important functions in protecting and moistening the eye as well as in expressive displays. These muscles constrict skin around the eye, reduce the eye opening, and close the eye. It has three parts, an outer or orbital part, an inner or palpebral part in the eyelids, and a small
lacrimal part near the tear duct. The outer part
originates in the medial part of the orbit and runs around the eye via the upper eye cover fold and lid and returns in the lower eyelid to the palpebral ligament; the palpebral part
originates in the palpebral ligament and runs above and below the eye to the lateral angle of the eye. These two muscles form concentric circles around the eye. Action of the palpebral part is often involuntary, as in the blink reflex.

Orbicularis oculi is innervated by zygomatic and frontal branches of the facial nerve (VII) and is supplied with blood by the superficial temporal and facial arteries.